The present invention relates to a gas discharge display apparatus having a gas discharge panel, such as a plasma display panel, and a manufacturing method for the same.
Large screen display devices with high picture quality, such as that produced by high definition television (HDTV), have recently become the focus of much expectation. As a result, research and development of display devices such as cathode ray tubes (CRTs), liquid crystal displays (LCDs), and plasma display panels (PDPs) is taking place. These various types of display devices each have the following characteristics.
CRTs have excellent resolution and picture quality, and are widely used in conventional televisions and the like. The large increases in depth and weight required to produce a large screen CRT, however, are problematic, and solving this difficulty is crucial for the development of such CRTs. Due to this problem, it is believed to be difficult to produce a CRT with a large screen of more than 40 inches.
LCDS, on the other hand, use less electricity than CRTs, and are extremely light and slim. Nowadays, LCDs are being increasingly used as computer monitors. However, typical LCD, which uses a thin film transistor (TFT) screen or similar, has an extremely intricate structure, and so manufacture of such a device requires a plurality of complicated processes. These processes become increasingly complex as screen size increases, with the result that manufacturing yield decreases as screen size grows larger. This means that it is currently considered difficult to manufacture an LCD with a screen of more than 30 inches.
In contrast to CRTs and LCDs, PDPs are gas discharge panel display apparatuses that have the advantage of being able to realize a lightweight display with a large screen. Therefore, in the current search for the next generation of displays, research and development of large screen PDPs is being pursued particularly aggressively, and products with screens of more than 60 inches are being developed.
In a basic PDP structure, a glass substrate, on which a plurality of pairs of display electrodes and a plurality of barrier ribs are arranged in a stripe formation, is placed in opposition to another glass substrate. Phosphors in each of the three colors red, green and blue are applied hermetically to the spaces between the barrier ribs. The two glass substrates are then sealed together so as to be airtight, and a discharge gas enclosed in the discharge spaces between the barrier ribs and the two glass substrates. Discharge from the plurality of pairs of display electrodes causes the discharge gas to generate ultraviolet (UV) light, and this in turn causes the phosphors to emit light. Here, FIG. 13A is a diagonal view of a pair of conventional PDP electrodes 22 and 23 arranged on top of a front glass substrate 21, and FIG. 13B is an aerial view of the pair of electrodes 22 and 23 looking down in a direction z. The electrodes 22 and 23 shown in the drawings are formed from strip-shaped transparent electrodes 220 and 230, on which metal bus lines (bus electrodes) 221 and 231 are overlaid. A numerical reference 340 indicates cells for image display divided by neighboring barrier ribs 30, so that, for example, cells 340 having phosphor layers in the colors red, green and blue are arranged in parallel with the x direction, forming pixels for achieving a color display.
PDPs such as this one can be divided into two types, direct current (DC) and alternating current (AC), according to the driving method used. AC PDPs are thought to be more suitable for producing a large screen device, and thus are the most common type of PDP.
However, current demand is for electronic products that limit consumption of electricity to as low a level as possible. In this climate, the need for PDPs that can be driven using a small amount of electricity is growing. In particular, the current trend toward development of large-screened and high-resolution PDPs has led to an increase in the electrical consumption of such PDPs, and so there is an increasing demand for energy-saving techniques. It is hoped that such techniques will reduce the electrical consumption of PDPs.
However, merely carrying out strategies for reducing the electrical consumption of a PDP causes the scale of discharge generated between the plurality of pairs of display electrodes to be reduced, and satisfactory light emission becomes unachievable. As a result, it is necessary to maintain satisfactory display quality (in other words satisfactory luminous efficiency) while limiting electrical consumption. If insufficient light is emitted, the display quality of the PDP will be reduced, so merely decreasing the electrical consumption of the PDP cannot be said to be a valid strategy for increasing luminous efficiency.
Research is being conducted into a method for improving luminous efficiency by, for example, raising the efficiency with which phosphors convert ultraviolet light into visible light. However, at this point in time no noticeable improvements have been observed by using this method, and there is still room for further research to be conducted.
The above problem is not confined to a gas discharge panel such as a PDP (that emits light by generating a discharge within a glass container filled with discharge gas), and also exists, for example, in other gas discharge display apparatuses that provide a gas discharge device other than a PDP.
Currently, it is thought to be extremely difficult to preserve the appropriate luminous efficiency in this kind of gas discharge display apparatus.
The present invention is designed to overcome the above problems, and has as its object the provision of a gas discharge display apparatus capable of preserving appropriate luminous efficiency, and by this means achieving a lower level of electrical consumption than is conventionally possible, while preserving the scale of discharge required to achieve satisfactory display quality, and of a manufacturing method for the same.
The above object is realized by a gas discharge display panel in which a plurality of cells filled with a discharge gas are arranged in a matrix pattern in a space between first and second substrates placed in opposition to each other. At least one pair of display electrodes are arranged on a surface of the first substrate facing the second substrate so as to span the plurality of cells. Each pair of display electrodes includes two extension parts that extend lengthwise along the matrix, a plurality of inner projections electrically connected to each extension part, and protruding toward the other extension part, and at least two connectors arranged, keeping a fixed interval therebetween, between the two extension parts. Each connector electrically connects at least two inner projections provided for a same extension part.
In the present invention, display electrodes are formed by combining inner projections and connectors, so the discharge generated in the gap between a pair of display electrodes is gradually expanded by the inner projections and the connectors connected to the inner projections. In particular, since the connectors and inner projections are electrically connected, satisfactory expansion of discharge can be achieved along the display electrodes.
Furthermore, a plurality of apertures are formed between the extension parts and the plurality of connectors. Naturally a charge is not accumulated in these apertures, and so an electric charge accumulated on the display electrodes is reduced to less than in the prior art when discharge is started by driving the gas discharge display apparatus. Once discharge has started, it also expands by diffusing to the apertures, and so a satisfactory level of discharge can be achieved in spite of the presence of the apertures.
Such characteristics enable the gas discharge display apparatus of the present invention to reduce the charge accumulated on the display electrodes, and restrict power consumption, as well as maintaining a display quality that is at least equivalent to that of a conventional device. In other words, the present invention effectively reduces the surface area of the display electrodes in the display unit (electric capacity), reducing excess power consumption, and realizing a gas discharge display apparatus with superior luminous efficiency.
References such as Japanese Laid Open Patent H8-250029, and U.S. Pat. No. 5,587,624 disclose an example of a technique for providing a plurality of projections for the display electrodes, thereby improving luminous efficiency and the like.
However, these references do not disclose a technique like the one described in the present invention for providing connectors to electrically connect the at least two inner projections, and since projections are formed independently, alignment is difficult to achieve. The present invention, provides the display electrodes with connectors, achieving a superior effect by avoiding both the large increases in manufacturing costs caused by variations in accuracy during manufacturing, and deterioration in image uniformity.
An actual example of the gas discharge display apparatus of the present invention may be a PDP or similar device. PDPs with larger screens are currently being developed, and this leads to increases in power consumption. Consequently, the present invention is particularly effective when applied to a PDP.
The present invention may arrange a plurality of connectors on each extension part.
Furthermore, the inner projections and the connectors may be manufactured of a transparent electrode material, and the extension parts of a metal material. Here, the extension parts are bus lines. Since the transparent electrode material has a lower electric resistance than the metal material, if this construction is applied in the present invention, power consumption is likely to be further reduced.
Furthermore, the present invention, outer projections may extend from a side of a bus line in an opposite direction to inner projections. When such a technique is used, in addition to the above effects, discharge expands from the bus line outward, and superior luminous efficiency can be achieved.
In addition, when a layer is formed so as to cover the at least one pair of display electrodes, areas of the layer corresponding to a minimum discharge gap between a pair of display electrodes may be formed of magnesium oxide, and other parts of the layer from a material with a lower electron emission yield than magnesium oxide (for example aluminum). This enables discharge to be generated more easily in an initial discharge period when the gas discharge display apparatus is driven.